Common Viral fish diseases

Common Viral fish diseases
Grass carp hemorrhage (hemorrhage of grass carp) is most grass carp Fingerling rearing stage of the disease, as early as 1978, the hydrobiology Institute to study the pathogen of this report. , Chinese Academy of Sciences, Wuhan University, Wuhan Institute of Virology, CAFS, the Yangtze River Fisheries Research Institute in China, and many units have also conducted in-depth research to this pathogen. International grass carp hemorrhage virus found in China, and the first was reported. Research personnel on grass carp bleeding disease virus of form structure and physico-chemical characteristics, and virus of nucleic acid nature, and virus and host between of mutual role, and virus of organization pathology, and different virus separation strains of nature features, and virus of serum learn nature, and immune control, many carried out has research (Chen Yanxin,, 1983; Deng summer,, 1985; Min Shuqin,, 1986; Fang Qin,, 1989; Ke Lihua,, 1990; Ding Qingquan,, 1990; Jiang Yulin,, 1991a).

Pathogenic viruses for 20 solid particles, diameter 50~80nm, vary because of different isolates, such as Chen Yanxin, (1983) reported the virus particle diameter is 53nm; Ke Lihua et al (1990) reported the virus particle diameter is 71nm. No lipoprotein envelope of the virus, had a double capsid. Viral genomic nucleic acid is RNA, made up of 11 segments of total molecular weight of about 15×10-6. Virus in rostral cell line ZC7901 in grass carp, grass carp, cell line, CIK, GCK84, fish fin Minnow cell proliferation in CF84.

Epidemic disease and harm hemorrhage in FRY, viruses mainly carp, herring also makes artificial infection of diseases. With up to 2.5~15cm of fish disease is the most common, and often caused the death of a large number of grass carp fingerlings. 25 ℃ below fish is a latent infection, when water temperature exceeds 27 ℃, the disease can be widely popular, high mortality rates, often up to 90% or more. Fish virus infection can have different symptoms, such as “red muscle” symptoms as muscle blood red gills are often anemic and pale, this small fish found in 7~10cm; “Red fin red gills” symptoms as the fin base and the gills congestion, disease-prone in the larger fish (13cm) and “diarrhea” symptoms are characterized by intestinal serious congestion, small and large grass carp may occur. These three symptoms can occur alone or both.

Pathological changes in small blood vessels extensively damaged the wall, the formation of microthrombi and infarct-like lesions cause tissues and organs. In liver cells, such as intracytoplasmic Eosinophilic inclusion bodies can be seen. Percentage amount of white blood cells, lymphocytes, red blood cells and haemoglobin was significantly lower than fish, monocyte percentage is significantly higher than that of fish. Serum alanine aminotransferase, isocitrate dehydrogenase, lactate dehydrogenase activity increased plasma levels of total protein, cholesterol-lowering. Intestinal bleeding is the main symptom of sick fish to swelling of the intestinal epithelial cells, Goblet cells increases intestinal epithelium and lamina propria stripping, lumen has a large number of red blood cells and pieces fall off the intestinal epithelium.

Detection and prevention of fish Reovirus antiserum was prepared on the basis of, through discontinuous EP and enzyme-linked immunosorbent assay (ELISA) methods on early diagnosis of disease, but also by Staphylococcus protein a coagglutination test, histopathological and electron microscopic observation of the preliminary diagnosis of grass carp haemorrhage. Through the artificial immune system can effectively control grass carp haemorrhage. Tissue pulp inactivated vaccine and inactivated vaccines can be used in the production of cell culture practice, supplemented by using immune booster (such as hyoscyamine) can enhance the immune effect. Certain herbs, the rational use of antibiotics and, to some extent, slow the effects of the illness.

Referred to research on the virus disease of grass carp Reovirus outer in detail, there are other relevant reports. Mao Shujian (1989) isolated from grass carp in the pathogenesis of Zhejiang reported a small virus particles, diameter 20~30nm, genome as a single strand of RNA, no envelope, after the preliminary appraisal is a small RNA virus.
CARP virus
Viral disease of carp have been found and reported the main spring carp Viremia, carp Gill of smallpox disease, necrosis, and following a brief introduction, respectively.

Spring carp Viremia
Spring carp Viremia virus (Spring Viraemia of carp virus,SVCV) are pathogens that can cause acute infections in carp. After infection by the virus of carp in the pathogenesis of water temperature below 15 ° c in spring, and severe bladder inflammation symptoms are severe abdominal edema syndrome, and can often lead to secondary bacterial infections. Debate about the origin of the problem some, originally thought to be bacteria, until 1972 Fijan reported issued by the separation of infectious virus to be determined. SVCV genus rhabdoviridae family, this virus particles were rod and (or) bullet-shaped, long 135~380nm of mature virus particles, with a diameter of 45~95nm. Nuclear protein nucleocapsid consists of spiral wound (minus-strand single-stranded RNA and the n protein). Spring carp Viremia of outbreaks of water-related, and the optimum temperature for 16~17℃. Viruses can be spread by susceptible fish feces in the water, or some blood sucking parasites such as Lei Shi (Argulus Foliaceus) and inchworm fish leech (Piscicola geometrica Linnaeus) spread. In a State of nature, other fish besides carp, grass carp can also be infected. SVCV cells in some fishes such as FHM, effects of the EPC, and cause cell lesions. The pathogen by serological methods for diagnosis. May refer to several methods to control the SVCV: avoid the incoming virus source; Vigorously carry out drug cultivation of seedlings; Artificial control of water temperature (20 ℃ farmed fish); Immunization.
Necrosis of common carp Gill disease
Necrosis of common carp Gill (Gill necrosis of CARP) by Soviet scholars Shchelkunov and Shchelkunova (1981) reported that from a disease characterized by necrosis of Gill fish gills and kidney were isolated in virus, the virus can replicate FHM cells and infected fish disease. Preliminary judgment that the virus belongs to iridovirus.

CARP smallpox disease
Smallpox disease of carp (fish POX) smallpox disease is carp common diseases before and after winter, fashion is very broad. Main round belly Chub and carp, crucian carp, effects on fish growth and the value of goods. Fijan, (1983) isolated from diseased fish herpes virus (Herpesvirus). Jiang Yulin (1991b) reported the results of electron microscopic observation of carp smallpox pathogen. The typical symptoms of varying size in fish body surface is covered with massive white mucus, wax-like increase of biological, namely smallpox. These smallpox combined with the body surface of the fish is firm and can be scratched off with a knife. Remove smallpox into thin slices, electron microscope, there are a large number of virus particles present in the cytoplasm. Virus core 20 facets of Herpesviridae. Virus particle diameter 140~160nm, capsid diameter is 80~100nm. Virus nucleocapsid formed in the cell nucleus, get when the capsid bud through the nuclear membrane envelope, and gains the ability to infect cells. The viruses in epithelial cells of carp (EPC) cells, form a syncytium. After artificial infection test vaccinations to health carp virus suspensions in vivo, in 10~15℃ conditions 1 month later was get smallpox by inoculating the body surface of the fish. Pocked suspension with scratch after inoculation with Lei Yue Mun can be copied out in the laboratory with the same natural onset of symptoms, and by changing some of the environmental factors that control the occurrence of smallpox and disappeared. Under natural conditions, the virus can spread through mucous membrane exposure and contamination on the surface of the water. In addition to viruses, but Jeney (1995) on carp’s other diseases such as bacteria, fungi and parasites, a more comprehensive review of the progress, and control of fish diseases of great value.
Eel virus disease
Both at home and abroad have reported on eel virus, see the research.
Virus disease of eel type: virus of European eel (eel virus european,EVE), eel virus (eel virus,EV), eel Bush virus (cauliflower disease of eels virus), eel slug virus (rhabdovirus of eels), eel blisters virus (vesiculo virus ofeels). There is popular among other fish and infections viruses such as infectious pancreatic necrosis virus (infectious pancreatic nerosisvirus,IPNS), herpes viruses (herpeslike virus), Viral Hemorrhagic Septicemia virus (viral haemorrhagic septicaemia virus,VHSV) can also be infected eels (Castric, 1992).

Eel virus disease symptoms and pathogenic nature eel virus pathogen of the earlier study was EVE. Japan imported from European eel FRY in the 2nd year (1969), outbreaks of disease, and about half of eel deaths deaths a year in the same place only eels reach 2 700T. Only in 1973 on the eel from kidney disease viruses isolated. This double-stranded RNA virus of the genus eel virus pathogen, serology and infectious pancreatic necrosis virus (IPNV) close to the Ab strain, physical and chemical properties are identical to the IPNV. By EVE caused disease occurs mainly in winter, in Japan and China’s Taiwan caused Japan eel dead. 8~14℃, 4~26G 55% of the elver 20D mortality after infection. Main symptoms and pathological changes are: dying eel in temporary muscle spasms, or eels local rigid body, anal and some eels abdominal congestion, renal enlargement, ascites, Glomerular seriously damaged, some eels spleen necrosis of large areas. In naturally infected eels, Gill lamellae and hyperplasia of fusion phenomena (Huang Qiyan, 1993).

SchwantzPeitzner (1976) isolated from patients suffering from cutaneous Papilloma eel blood out of the EV. Viruses are round, with a diameter of 46~54nm. After viral inoculation of eels, do not produce any symptoms, but the virus particles in the cytoplasm of the host. Nagabayashi et al (1979) from the eel are ill isolated another virus in the blood, known as the eel Bush virus (cauliflower disease of eels virus). This virus, orthomyxovirus family (Orthomyxoviridae), type, diameter 90~140nm, 10nm long protrusions on the surface structure. Disease of eel head and lips clearly covered with hyperplasia of squamous cells, forming cauliflower-like head. Viruses are sensitive to ether, poisoning at 4 ℃ for 3 weeks, chickens and sheep red blood cell lectin. Virus on FHM cell culture cultivation temperature is 15 degrees Celsius.

In addition to the eels serological relationships of different isolates studied (Ahne, 1987). Jorgensen et al (1994) reported that scientists from several countries, such as 1977-1992 in Denmark and the United Kingdom, and France and the Sudan on 2 092 Man Chi virus test result. They got 91 virus samples, analysis showed that, of which 44 eel rhabdoviridae (eel rhabdovirus EVEX/EVA) genus Vesiculovirus (vesiculo group); 3 eel elastic-like virus belongs to the genus of rabies virus (Lyssa group); 38 infectious pancreatic necrosis virus (IPNS); 5 types of herpes virus, and Viral Hemorrhagic Septicemia virus 1. Visible, eel virus disease of harm exists and has caught the attention of scientists.

About the research profile of the first reports of eel eel virus virus disease is Chen Yanxin, (1992), suffering from a bloody opening of eel virus was found in blood cells. Virus particles 20 dodecahedral symmetry, consisting of a core and wrapped in film composition, particles with an average diameter of 70nm, inner core to 40nm. Mouth disease of eel in red blood cells and white blood cells, are seen under the electron microscope virus particles, but in the form of the virus found in the two size difference: virus 70nm in diameter in the red blood cells, capsule; In the white blood cells of diameter up to 40nm, not capsule. Fish is the main symptom mouth open not closed, in addition to sick fish is dark grey, head up, membrane bleeding in the mouth, and pectoral, pelvic and abdominal bleeding bit. Infected cells had abnormalities, such as wider or forming irregular folds of nuclear envelope; Round the swelling of mitochondria were vacuolated, and some contain Flocculent particles; Rough endoplasmic reticulum threshing and vacuolation. Recently, such as Tao Zengsi (1997) reported on eel “swim” pathogens research results show that the disease is caused by the “coronavirus-like virus” causes. Their condition is a disease of eel down in the water ran, spin crazy tour, muscle cramps, chest bruises; At necropsy liver enlargement. Histopathological examination showed liver, kidney and nervous cell degeneration and necrosis of the heart.
Viral diseases of rainbow trout
Rainbow Trout for cold water fish (cold water fishes), natural distribution in the United States, and Canada, and Mexico and other places. Trout began in 1959, but since intensive farming in 1983 from the United States, and Japan began only after the introduction of fine varieties of trout. Has been studied in detail in several important virus diseases of fish, at least three serious threats to farming of rainbow trout, which is infectious pancreatic necrosis (infectiouspanereatic necrosis,IPN), Viral Hemorrhagic Septicemia (viral haemorragic septicemia,VHS) and infectious hematopoietic necrosis disease (infectious hematopoietic necrosis,IHN)。

Infectious pancreatic necrosis disease
Rainbow Trout research on infectious pancreatic necrosis and viral pathogens is the Wolf (1959) began after reports this is a viral disease. Wolf (1988a) reviewed more than 200 articles in the literature based on the history of study of infectious pancreatic necrosis virus of fish, host and geographic distributions of, physicochemical properties, separation, identification, immunity and control aspects are described in detail. Since this virus serious, popular, as a first class national fish quarantine and quarantine objects. Main symptoms of infectious pancreatic necrosis is perpendicular to the fish swim, fish blackened, proptosis, swelling of the abdomen, anus and often drag cable-like mucus. Infectious pancreatic necrosis virus (IPNV) sensitive many fish, such as some varieties of salmon, trout, salmon, mainly against day-old FRY and 14-17 species, mortality rates of up to 80%~100% when the water temperature 10~12℃; Other fish from 20 families also in detecting IPNV and most poisonous fish illness did not appear. Studies have shown that, IPNV levels can not only spread poison led to vertical transmission through the egg. The most visible pathological changes of pancreatic necrosis, cell nuclear pyknosis and fractured, some of the inclusions in the cytoplasm of the cell. IPNV belongs to the double-stranded RNA viruses, with 20 grain, about 60nm in diameter, there are RNA-dependent RNA transcriptase. IPNV RTG2, R1, PG and CHSE cold-water fish cell lines cell proliferation and caused varying degrees of lesions. In Rainbow Trout imported in 1987 from the isolation of IPNV, and serological identification of IPNV rapid detection method of rainbow trout was also established (Jiang Yulin, 1989, 1990).

Viral Hemorrhagic Septicemia
Viral Hemorrhagic Septicemia virus (VHSV) is a bullet-shaped virus, can cause acute and subacute infection of rainbow trout mortality as high as 80%. Histopathological characteristics of the hematopoietic organs such as the spleen, kidney, and pancreatic necrosis. Acute type characterized by proptosis, bleeding and rapid death; Chronic infection characterized by slow movement disorders, anemia, and death. Epidemic in late winter and early spring, water temperatures below 14 c during outbreaks. Pathogenic diagnosis can be formed by taking the sick fish entrails, blood, or ascites for virus isolation, inoculated tissue homogenate or body fluids of sick fish to RTG2, CHSE, FHM, EPC or PG cells, 15 training 1~2D lesions can occur, complemented by neutralization test or fluorescent antibody technique can be used for isolation of strains for identification.

Infectious hematopoietic necrosis disease
Infectious hematopoietic necrosis virus (IHNV) rhabdoviridae, Huang Qiyan (1993) on the virus and the disease has been introduced. Infectious hematopoietic necrosis disease initially in the United States occurred, found in North America and Japan as well. Zhao Zhizhuang et al (1993), reported that the China’s Benxi rainbow trout virus IHNVB separation of hybridoma cell lines, monoclonal antibodies and ELISA detection method. Leng (1995) wrote that with IHNV from broodstock to eggs or sperm can be virus progeny, and a descendant of fish can survive a few individuals, these fish survive once it can no longer be IHNV infections cause disease, electron microscopy and molecular techniques (PCR) showed that, in those still surviving fish can be found in the presence of RNA of IHNV. Why the surviving fish disease but also against IHNV infection? Drolet et al (1995) studies have solved the mystery: the original flawed virus particles in these fish (DI), and DI for IHNV interfere with infectious, which shows the fish a molecular mechanism of resistance to viral infections, also explore the treatment of fish disease provides a new way of thinking. In addition in recent years has reported on other viral diseases of rainbow trout (Nylund, and others, 1995).
Mandarin fish siniperca chuatsi virus edit this paragraph
The Mandarin fish siniperca chuatsi [Siniperca chuats (Basilewsky)] virus abroad about the Mandarin fish siniperca chuatsi virus disease research are yet to see, but in recent years the Mandarin fish siniperca chuatsi diseases in Guangdong and other places popular with serious, illnesses mainly Mandarin fish skin bleeding point, Gill pale; Anatomical visible damage caused by a lot of bleeding, liver, spleen, gall bladder and bowel congestion and significantly enlarged. And harm of the disease in 1993, occurred only in a small number of farms, but extremely fierce, against the 1994-1995 of the same diseases, and in the Pearl River Delta is widespread. Incidence of tens of thousands of hectares of fish ponds 60%, serious disease of fish mortality than 90%. Use medications such as antibiotics, to no avail; Bacteria pathogenic bacteria could not be found. Researchers at the Institute of hydrobiology of the Mandarin fish siniperca chuatsi in fulminant epidemic of liver, spleen and heart tissue thin section electron microscopy, found in the cytoplasm, nucleus and cell gap distribution there are viral particles in. Virus morphology is spherical, its diameter is about to 280nm. Filtration and degerming crude after virus vaccination to fish cells in monolayer culture can make cells lesion; Healthy sauce using crude extract of virus or amplification of the virus infection in cultured cells, could cause the morbidity and mortality of the Mandarin fish siniperca chuatsi. Mandarin fish siniperca chuatsi on health (both artificial and natural infection of fish) were dissected, and the gills, liver, spleen, heart and renal histopathological observation 5 organs, confirmed the 5 organs of the Mandarin fish siniperca chuatsi diseases have taken place, and artificial infection of fish and fish in the pathogenesis of disease in natural state consistent with the pathological condition. These results show that of Mandarin fish siniperca chuatsi viruses discovered by (siniperca chuatsi virus,SCV) is the Mandarin fish siniperca chuatsi fulminant epidemic disease (such as Zhang qiya, 1996a).
Spotted catfish channel catfish virus disease
Spotted cross channel catfish virus disease (channelcatfishvirusdisease,CCVD) spotted catfish channel catfish virus (CCV) is a herpes virus, which can cause spots cross channel catfish (IctaluruspunctatusRafinesque) FRY and young fish acute hemorrhagic diseases, mortality is as high as 100%. Fijan, (1970) reported the first results of CCV. Wolf (1988b) study reviews the progress of the CCV, introduced the history of CCV, infection caused by illnesses and pathological changes, physical and chemical properties, diagnosis and isolation, such as immunization and prevention. CCV as spherical particles, the capsule of a virus particle diameter 175~200nm, capsid diameter of about 100nm, genome for double-stranded DNA. CCVD outbreak is related to water temperature and fish age, when water temperature at 25 ℃, when the fish susceptible to, the incubation period is only 7~10d and acute onset. Disease characterized by uncoordinated spiral swim fins and bleeding at the base of the tail. Anatomical visible disease of kidney, spleen enlargement, internal bleeding, and pathological examination and hematopoietic necrosis, nuclear pyknosis and vacuolation. Spotted catfish channel catfish farming in some parts in China has taken shape, with the promotion of intensive farming techniques, more and more serious diseases, to establish awareness is very important. Serological and molecular biological diagnostic techniques have been successfully used in diagnosis of CCV (Wise, 1985), application for reference. Also worthy of special mention is the world’s first virus recombinant gene and its expression in fishes have been successful (such as Zhang, 1996), which is aimed at the CCV made an important study. This development heralded hopes to use genetically engineered vaccines to prevent viral diseases of fish.

Common fish diseases control

Common fish diseases control

Fish life in the water of life, and environmental factors is complex, often hit by viruses, bacteria and parasites, so fish is sick for many reasons, often cause large numbers of deaths after the fish is sick, even if the fish is sick is not death but also seriously affected the growth of fish. Like other animals do not treat fish diseases and treatment, have difficulties in water treatment and isolation. In aquaculture, therefore prevention is an important measure to prevent fish disease, prevention is more important than cure.
First, the prevention of fish disease
Prevention of fish disease from three aspects, one is to destroy pathogens and predators, second is to improve the living conditions of fish, making the environment conducive to the growth and health of the fish, the third is enhanced resistance of the fish.
(A) the clear pond
Put pond water dry or drain, clearing the pond bottom and Tong Geng, trash, weeds, fix Geng feet to prevent water seepage, leakage, keep the pond bottom mud 10cm, Tang 5-7 at the end of the day, sunlight exposure, fish pond, pathogens and predators for biological removal of more complete.
(B) the fish pond sterilization
1. Health lime disinfection: ponds clearing Hou, in dry pool conditions Xia with health lime 50-75 kg/acres, full pool spilled, health lime with wood barrels or plastic barrels, container Sheng water dissolved Hou, hot spilled, as bottom also left 5-10cm of water, is can without container, in pool end of uniform of dug many shallow pit, will health lime directly put to each small pit,, sucking hydration open Hou, will lime water spilled full pool, again with rake will pit within of lime rake moving mix. 1-2 days can be basal, 2-3 days after fresh water, 5-6 days can fish.
Another is water disinfection methods, such as fish ponds and drainage problems or anxious when species, this method can be used, depth of 1 m per acre quicklime 130-150 kg, evenly sprinkle it in the whole pond, 7-8 days after the fish.
2. Bleach disinfection. After draining the pond water with bleaching powder 4-5 kg/acre, water sprinkle it in the whole pond, amount of bleach with water to a depth of 1 m per acre 13-15 kg, 5-6 days after fish, note that bleach does not use a metal container holding water dissolves. Amount of chlorine bleach in about 30%, that pungent smell bleach large, insoluble in water heating.
3. Tea disinfection. Average water depth of 1 m per acre when dosage is 40-50 kilograms, tea cake is first crushed into small particles, is immersed in the solution for a day and a night, even slag with juice evenly sprinkle the whole pool, tea cake can kill wild fish eggs, tadpoles, snails, frogs and aquatic insects, but not do much help to kill bacteria and parasites.
Three Qing Tang disinfectants, lime and chlorine bleach has a number of advantages, kill bacteria more thoroughly, and lime as well as improving water quality.
(C) species disinfection
Species will inevitably bring some pathogens, after disinfection of pond clear, with no stocking of fingerlings disinfection will bring pathogens to the water, once the conditions are right, multiply and cause disease. Disinfection drug dipping method is often used for species.
1. Bleaching powder and copper sulphate mixture for dipping. 1 cubic meter water with bleaching powder 10 g and 8 g copper sulfate. Note: bleaching powder and copper sulphate after dissolving contact separately by different blending mixture, dipping fish in the 10-20 c 20-30 minutes.
2. Potassium permanganate solution dipping. 1 cubic meter of water used 20 grams of potassium permanganate, when dipping the fish 10-20 1-2 hour, liquid preparation used, over a long period of failure.
3. Dipping salt solution. With sputter the salt solution, 10-20 dipped Fingerling 4-5 minutes.
Any solution when dipping fish, dipping the length of time appropriate to the species healthy and low temperatures to make appropriate adjustments.
(D) water disinfected on a regular basis
Most fish disease of occurred, are has must of seasonal, many fish disease in 4-October popular, especially 6-September, water temperature increased, fish growth speed speed up, disease original body and predators biological large breeding, fish disease also easy occurred, so strengthening farming water of feeding management, insisted regularly water drug disinfection, improved water environment, is prevention fish disease occurred of important measures.
1. In April, and in late May to mid June, monthly 90% crystals of dipterex on aquaculture water disinfection to kill parasites, dosage is 0.5 grams per cubic meter, surface 1 m depth for 6-7 two per acre. 1-2 acres of fish ponds of small bodies of water, and sprinkle it in the whole pond methods available, large surface cannot be splashed all over the whole pool of cases, methods that can be used near food bags hanging bag, hanging 3-6, 100-150 grams per bag charge for 2-3.
2. June early with bleach or health lime on water disinfection sterilization, bleach dosage for 1 cubic metres 1 grams, dissolved Yu water full pool spilled, larger water can used hanging basket method, each only baskets within loaded drug 100-150 grams, hanging 3-6 only basket, hanging in food field near, or with health lime on water sterilization disinfection each acres water depth 1 meters dosage for 15-25 kg, dissolved water full pool spilled, larger water with health lime can in food field around slightly poured reuse volume, water other place to as spilled to.
From late June to early July with copper sulphate and ferrous sulphate mixture to sprinkle it in the whole pond, Protozoan parasite-killing, prevent the occurrence of protozoal disease, the dosage of 1 cubic meter 0.7 grams, which is 5:2, or bagging method, each containing 100 g, 40 g of ferrous sulfate copper sulfate, General hung 3-6 bags.
3. From July to September with the increase of water temperature bacteria multiply, are prone to diseases and, therefore, every 20-30 days applying bleaching powder or lime pool splashing or bags hanging basket method of killing pathogens, the prevention of fish disease.
Second, the diagnosis and treatment of several common fish diseases
1. Red grass carp disease
Red skin disease is by fluorescent very hair Bacillus invaded for netting and the handling in the skin injured of fish body and caused, main symptoms is: fish body local or big Department congestive, and inflammation, and scales off, especially fish body sides and the abdominal most obviously, part or all fin article of base Department congestive, fin article shoots end rot, fish of Shang jaw and the Gill cover part congestive, rendering block erythema.
The disease can occur from early spring to winter, but are more common in late spring to early autumn, the main harm grass carp.
Treatment methods:
(1) the bleach: water treatment 1 gram per cubic metre, water sprinkle it in the whole pond.
(2) five times: 2-4 grams per cubic metre of water treatment, five times a mash with boiled water for 1-2 hours, whether residue or juice to sprinkle it in the whole pond.
(3) the bacteria with the exception of the disease outside the skin, muscles, causing lesions in fish, will invade the blood of fish, except for drugs, must also be used for internal use, in accordance with the description of the medicine used.
2. Gill-rot disease
Fish Gill-rot disease is caused by damage caused by Neisseria mucosa into the gills of a fish, the main symptoms are: sick fish often stray du tour, slow, loss of appetite, or not eating, body color black, especially on the head is black, so it is also called “Wu-blast.” Fish Gill rot disease white, often accompanied by sludge and slime, and severe congestion on the inner surface of the operculum, the middle portion of the skin is often eroded into a small transparent window, also called the “open window”.
This disease is often found in the grass, herring, Bighead carp, carp and other fish, mainly carp, 4-10 months the water temperature 20 deg in fashion in General, often with red skin, enteritis diseases in grass carp at the same time.
Treatment methods:
(1) lime sprinkle it in the whole pond, depth of 1 m per acre, is 15-20 kg.
(2) bleaching powder sprinkle it in the whole pond, water 1 gram per cubic metre.
(3) five times child sprinkle it in the whole pond, 2-4 grams per cubic metre of water treatment, warm water immersion, whether residue or juice spilled.
(4) birds with erythromycin and sprinkle it in the whole pond, 0.3 grams per cubic metre of water medication the next day, mix feed will this medicine taken orally, by 100 kilograms of fish on the first day for 4 g, the second through sixth days halved.
(5) water depth of 1 m per acre with 2 kg rhubarb, 0.3% ammonia-soaked for 10 hours, sprinkle it in the whole pond, rhubarb-ammonia ratio is 1:20.
3. Enteritis diseases
This disease is caused by intestinal gas production a single Spore, and the main symptoms: fish, loss of appetite, slow, from the single swim, abdominal swelling, Erythema, swelling, the anus, and tap in the abdomen, anus and a light yellow mucous outflow, intestinal inflammation, hyperemia. Often associated with the Gill-rot disease of grass carp at the same time.
Season May-September, major hazard 1-2 carp, water temperature is 20 degrees or more.
Treatment methods:
Treated with oral and topical medication in conjunction. For external use 1 gram per cubic meter water used bleach spilled over the whole pool or the quicklime sprinkled over the pool, water depth of 1 m is 15-20 kg per MU.
Medicine medicine can be purchased according to the directions, the other herbs that are available are as follows:
(1) garlic: per 100 kg of fish with garlic 0.5 gram (mash and blend in the flour or rice flour) and 200 grams of salt per 5 kg of feed, mix well for 3 days with fresh grass, once a day.
(2) to acalypha: hay per 100 kg of fish of 0.5 g or 2 kg fresh grass mixed inside the bran, flour, feed, for 3 consecutive days, one day at a time.
(3) hydropiper and acalypha: hydropiper per 100 kg of fish and acalypha 1 kg mixed with water 5 kg, boiling 1-2 hour, after cooling, mix feed, continuous feed 3 days, one day at a time.
These three kinds of bacterial fish diseases, often complicated and prone to infection and, therefore, prevention and treatment of fish disease and fish disease prevention should be emphasized.
4. Viral haemorrhagic disease
Hemorrhagic disease is mainly caused by herpes virus, characterized by three types of symptoms:
1. “Red muscle” type: this type is more common in the smaller grass species, fish had no significant bleeding or only minor bleeding, but grilled in addition to skin, muscles visible point or massive congestion, when muscles are bright red, Gill was port-congestion or gills appear “white gills.”
2. “Red fin red operculum” type: fish’s operculum, fin base, head, eyes, mouth and other significant congestion, sometimes scales also have congestion, but muscle congestion is not obvious. Mainly in the large grass carp has come.
3. “Colitis”: the fish skin and muscle pump is not obvious, but cut intestinal visible in whole or in part with a bright-red, mesenteric sometimes dotted congestion, and enteritis of distinction, not a mesentery, intestinal inflammation, ulcers.
Treatment methods:
(1) per acre of water depth of 1 m by 0.5 kg rhubarb, grind into fine powder, fried boiled or soaked in water overnight, mixed feed and bait, and continued for 5 days, then 0.7 grams of water per cubic metre sprinkle it in the whole pond with copper sulphate.
(2) water depth of 1 m per acre, with rhubarb, Cork 0.5 kg 0.5 kg, scutellaria 0.5 kg, Berberine, salt 0.1 kg 2.5 kg, 10 kg of lime, mixed pulp and sprinkle it in the whole pond.
(3) drugs that can be purchased to make a good, used according to the instructions.

1. “Red muscle” type: this type is more common in the smaller grass species, fish had no significant bleeding or only minor bleeding, but grilled in addition to skin, muscles visible point or massive congestion, when muscles are bright red, Gill was port-congestion or gills appear “white gills.”
2. “Red fin red operculum” type: fish’s operculum, fin base, head, eyes, mouth and other significant congestion, sometimes scales also have congestion, but muscle congestion is not obvious. Mainly in the large grass carp has come.
3. “Colitis”: the fish skin and muscle pump is not obvious, but cut intestinal visible in whole or in part with a bright-red, mesenteric sometimes dotted congestion, and enteritis of distinction, not a mesentery, intestinal inflammation, ulcers.
Treatment methods:
(1) per acre of water depth of 1 m by 0.5 kg rhubarb, grind into fine powder, fried boiled or soaked in water overnight, mixed feed and bait, and continued for 5 days, then 0.7 grams of water per cubic metre sprinkle it in the whole pond with copper sulphate.
(2) water depth of 1 m per acre, with rhubarb, Cork 0.5 kg 0.5 kg, scutellaria 0.5 kg, Berberine, salt 0.1 kg 2.5 kg, 10 kg of lime, mixed pulp and sprinkle it in the whole pond.
(3) drugs that can be purchased to make a good, used according to the instructions.

10 tips for summer prevention of fish disease

10 tips for summer prevention of fish disease

With the advent of the summer hot season, the high season is the fish in aquaculture during the use of drugs is very frequent. But there are many users do not understand the characteristics of aquaculture fish disease control process of drugs, improper use of fishery drugs, the result not only cause economic waste, but do not receive good results. This paper introduces the ten tricks fish medication to help farmers safe, effective medication to achieve healthy farming.

    1. To remedy. Blind administration is taboo fish diseases prevention and control, so that both reach the purpose of prevention and treatment of disease, but also cause economic waste, even from the side effects. Fishery drugs chosen scientific premise is accurate diagnosis of fish diseases, a comprehensive understanding of the nature and mechanism of drug prevention, so that remedy. One must not use illegal drugs, such as chloramphenicol, norfloxacin, furazolidone, sodium pentachlorophenol, malachite green and so on. The second is to choose the appropriate medication for the condition. The third is to prevent allergies to drugs different farmed species.

    2. Drug administration time is generally in the evening before, after throwing medicine, air temperature, water temperature is lower, can reduce fish stress and physical exertion. As the morning throwing drugs, due to dissolved oxygen in the lowest state, could easily lead to hypoxia floating head. Administration of sunlight at noon, will reduce the efficacy. The rain and thunderstorms should not be splashed drug at low pressure weather.

    3. spilled liquid, must not designated dumping applications wooden ladle, spoon evenly sprinkle the like. Quanchiposa should gradually downward from upwind downwind, so that drugs even spill. In particular pond corners is easy neglected, resulting in less than the area of ​​medication, sterilization, insecticide is not complete, so fish disease recurrence.

    4. To accurately measure the drug spilled water; mixed feed drugs to more accurately estimate the weight of fish, so as not to cause poisoning or drug overdose insufficient reach therapeutic effect. Allowed to calculate the volume of water is not enough and said the drug, a phenomenon often appear Quanchiposa because of insufficient dosage, the water reach a certain concentration, poor control effect. In contrast, excessive dosage, fish endure beyond the limit, then it will cause a lot of deaths.

    5. Before the drug according to claim spill fully dissolved with boiling water, warm or cold, the drugs can not spill particulate or lump, lumps, to prevent drugs are not fully dissolved, the water is still less than the required concentration, or drug particles are fish eating and death. As of lime slurry to spill, spill bleach should not be dry. Dissolving drug should pay attention to water temperature, such as insecticidal herbs require a temperature at 60 ℃ ~ 100 ℃.

    6. Do not spill drugs fed feed, preferably after the first feeding sprinkle drugs. However, when feeding bait, to make fish fasting, let the fish snatch, in order to reduce the residence time of bait in the water, in order to avoid the drug lost in the water, resulting in waste and efficacy of drugs can not reach.

    7. The two drugs used in combination, should pay attention to drug interactions, but also to melt mixing respectively. Two or more drugs in combination, or just use a drug, the effect has not disappeared, and then they use a second drug, may increase or decrease the efficacy occur, it may appear to enhance or reduce the side effects, it is necessary to pay attention to drug interaction effect. Usually farmers should not secretly mixed fishery drugs should be used under the guidance of technical staff. Such as lime can not be mixed with bleaching powder, copper sulfate, trichlorfon. Acidic drugs and basic drugs can not be mixed. Mix the drug should be preceded by tests conducted small water bodies, and then to use a large area, must not blind mix.

    8. When the fish floating head floating head or immediately after, not medication, otherwise it will create a large number of fish deaths.

    9. Notice of drug validity. The use of expired drugs, both reach the control effect of the disease, and some will produce harmful side effects. Prevention and treatment of fish diseases with drugs, especially bleach easy to damp failure, so use dried bleach powder, lime use block ash. Usually the drug according to the provisions safekeeping and use within the warranty period.

    10. The administration should be prepared before the preparation of some emergency measures, medication should be a period of observation in the field (2 hours to 4 hours), do not leave the pond, observe the fish situation, pay attention to whether there are unusual circumstances, if it is found fish floating head or not serious normal, should take timely measures.

Principle of using antibacterial drugs

Principle of using antibacterial drugs
(1) the correct diagnosis of the cause, rational use of drugs, strict control of the drug’s indications
Correct diagnosis is the primary condition for successful treatment. The main infectious diseases of fish bacterial diseases, viral diseases. Parasite disease called invasive disease. It is easy to diagnose the disease. It can be found that there is a large number of pathogens by the naked eye or by the microscope. According to the general symptoms of infectious diseases of fish and combined with laboratory tests to determine, but in practice, if we can exclude the parasite can use broad-spectrum antibacterial drugs for diagnostic treatment. After the observation for several days, if the effect is not obvious, it should be considered whether the virus disease, or re adjust the treatment plan. Should pay attention to the need for a certain period of time to play the drug, can not expect the day of the drug can quickly bear fruit. In fact, at one or two days after treatment, there is often a phenomenon of increasing mortality. This may be due to drug pathogenic bacteria in fish kills, prompting bacterial cells and release of endotoxin, acute poisoning caused by the death of the fish, this case is generally 3 – 4 days mortality will decrease, otherwise you should consider whether the drug overdose causes.
In addition, there is often a mixed infection of multiple pathogens in the late course of the disease. The common clinical car caused by grass carp gill rotifers and mixed bacterial infection, grass carp reovirus and gas production of single cell infection caused by enteritis, then there must be treatment options for different pathogens.
The correct diagnosis, selection of drugs according to drug indication, and adopt appropriate methods of administration.
(2) drug use time sooner rather than later fish once the disease, the symptoms appear loss of appetite, not feeding bait, oral drug on it can not afford to use fish in the pond after onset of action why drugs can control the disease? That’s because the drugs that are used to prevent the fish from the onset of the disease have a protective effect, so the real treatment for fish is not. It also shows that the more importance in fish disease prevention measures in yi.
(3) it is important to emphasize the importance of the immune system in the treatment of the disease. It is necessary to realize the importance of the immunity of the fish body.
(4) oral and topical use of drugs, external use of drugs is to play a role in the treatment of drugs on the surface of the body, and oral medication is to play its role in the absorption to control systemic infection. For bacterial diseases, whether it is a surface infection or systemic infection should be taken orally, external use of combination. For the infection of parasites in the body surface can be used only for external use, but sometimes it can also be effective for oral administration.
(5) to observe the effect of treatment in time, if the treatment effect is not obvious, we should analyze the reasons from the aspects of diagnosis, medicine, dosage, administration method, etc.. But should not be too frequent replacement of the drug; using a treatment regimen should be at least 72 hours after the observation to determine its efficacy, otherwise it will only result in drug abuse.
(6) to avoid the generation of bacterial resistance, which requires adequate dosage and treatment, and to pay attention to the use of different antimicrobial agents. Parasite resistance to drugs is also common.

Basic principles of drug use

Basic principles of drug use

Effect of judgment
Drug treatment can be judged from the following aspects: 1, to alleviate the symptoms and reduce the number of deaths. 2, food consumption increased. 3, normal swimming behavior. 4, body-color back to normal.
If antimicrobial treatment failure should be viewed against the following aspects and make medication adjustments: 1, incorrect diagnosis, pathogens are not clear, cause unclear and improper drug selection, 2, although accurate, but due to take chances, delayed the timing, because it’s too serious, most of the fish loss of appetite can not take bait. 3, drug problems, such as lack of effective drugs, or drugs not, or an arithmetical error, or dosing the right way, or using inadequate doses and treatments are not long enough, unable to control infection or cause relapse. 4, no elimination of sources of infection or cause is not eradicated, 5, remove any move sick fish, ponds, removal of stress factors such as illness, an increase in deaths. 6, the body’s defenses lower or disappear, 7, pathogenic bacteria develop resistance. 8, had dual infections. 9, physical and chemical characteristics of seawater and freshwater different, for many drugs (such as copper sulfate, oxytetracycline) efficacy have a great impact, required special attention.

Drug efficacy depends mainly on drug concentration in the blood and its duration, drug concentration in the blood only reaches the minimum inhibitory concentration (the minimum drug concentration required to inhibit the growth of bacteria) or more can play effect. Fish drug concentration in drug formulation, varies with the dose and method of administration, and the species of fish-related. Even the same species, but also because of its size, water temperature, food consumption varies depending on the conditions. In addition, the antibiotic concentrations in the blood are valid, should be based on susceptibility of pathogens. If pathogens are highly sensitive to this drug, the dosage can be less blood levels can be low 1 such as bacteria are only moderately sensitive, in terms of the quantity and blood levels must be high ¥ if the bacteria is not sensitive to drugs, strong resistance, even if the dose is large, nor to inhibit or kill bacteria.

Methods of drug use and its characteristics analysis

Methods of drug use and its characteristics analysis
The success or failure of the treatment is related to the use of the method. Even with the correct diagnosis, no effective methods of administration of drugs, right, still can not achieve the purpose of treatment. If you just put the drug into the water or in a casual way to mix the people in the food, it is expected to cure the disease, Deng is absolutely wrong. Medication methods in our country are mainly seven, introduce as follows now (different administration methods have their advantages and disadvantages, according to the actual situation to use)
1 oral
Oral administration refers to the drug mix feed made bait, cast after feeding drugs into the human digestive tract and is absorbed into the blood circulation of mermaid bodies. In feeding, temporary drug mix bait is also very commonly used oral administration, commonly employed in the turtle, eel and cage culture in. Bait is made of drugs, although with less drug in the loss of water, but there are also unfavorable aspects, such as drug in the finished product is easy to deteriorate degeneration, more important is due to the drugs have been according to a certain proportion of mixed feed, when the fish feeding rate decreased, the bait feeding may not up to a predetermined dose and effect.
Oral administration of the drug dosage less, easy to operate, no pollution of the environment, the fish body does not produce a stress response. But its biggest drawback is the treatment effect is affected by the fish in the moat of feeding ability, due to the many diseases of the first symptom is appetite decrease or loss of, so appropriate use in early onset. The administration methods of filter feeding fish (such as silver carp, eel) and feeding activity biological bait fish (such as Mandarin) have some difficulties.
Oral administration of drug treatment success is in the following three aspects is the prerequisite for the fish to feeding, good palatability of drugs, the drug can be absorbed in the digestive tract.
2 times over
Sprinkle refers to in the water for a long time using low concentration (but still effective concentration of drug, which is most commonly used in our country of a kind of administration method. Its efficacy is not affected by the appetite of Akira ring, as long as drugs do fully dissolved and sprinkling uniformity, all individuals can access to drugs. However, the use of the method of sprinkling, the drug can not be effectively absorbed into the body, although the water body of the pathogen has a better anti-virus effect. However, the efficacy of the drug is easily influenced by environmental factors, and it also has adverse effects on the environment and environment, and it is necessary to pay attention to the immune function of the fish. Because of the economic reasons, antibiotics are not suitable for all the way.
3, bath (immersion method)
Is a short period of time in a small volume of water to use high concentrations of drugs, compulsory fish by the drug, the body surface of fish. This method is usually used in the transfer of the pool and transport processes, and the treatment of ornamental fish diseases often use this method. The method has less dosage and the treatment effect is good, but it can be infected with the pond for a long time. Because the operation is troublesome, it restricted and in the operation process, poisoning and anoxia accident prone, so must be very careful, be sure to grasp the drug concentration and dipping time, abnormal timely evacuation. In addition, this method has a strong stress response to fish experience due to high drug concentration and mechanical operation, which affects the subsequent feeding and disease resistance.
4, hanging bag
Hanging bag for medicine refers to the drug loaded bags or baskets hung in cages or ponds feeding grounds near or other water environment, the drug use in the slow diffusion play a long time the prophylactic and therapeutic effect. When the bag is put in the bag, it should try to control the release rate of the drug, release the drug quickly, and it may cause drug poisoning. If the food is in the food field, it is necessary to make the drug concentration in the range of the fish, or it will affect the fish feeding.
5 Injection
The injection is the injection of the fish. By injection of different parts, injection and intramuscular injection and intraperitoneal injection. Intramuscular injection of general in front of the dorsal fin and lateral line in the middle of that fish the thickest part of, and the fish body is Eve joy, 30 ~ 40 Eve joy, angle and direction to head into the needle. The depth of the injection is not up to the size of the spine. Intramuscular injection is applied to the muscle tissue of non irritating drugs. Intraperitoneal injection needle position in the ventral and lateral line in the middle of the partial above, such as skilled, liquid can not leak, this than intramuscular injection effect. In addition, in the base of the ventral medial oblique Xiangyang Road in the direction of the needle is worth outline two injection method and injection to ogle medicine absorbed quickly, the effect is good, but the operation of the trouble, counterpoint to the stimulus is relatively large, used for parent fish and a few rare fishes and ornamental fish.
6 local smear
Topical is mainly used for treatment of pro’s or valuable fish skin lesions, commonly used pharmacological agents with ointment, gentian violet, iodine and hydrogen peroxide and other, because of the fish body wall newspaper slippery, and sometimes cream is not easy to smear up. This delivery method is usually used in the treatment of furunculosis when.
7, indirect administration
Indirect administration law refers to the drug feeding to treated bait biological science and then the accepted drug food organisms feeding to the treatment object, such as Kang fish only bait feeding activity and not feeding pellet feed, so only the first drug to bait fish feeding, and then switch to Mandarin. Some sea fish also belong to this situation.
Different drugs are applied to the different routes of administration many antibacterial drugs such as tetracyclines (including strong bad cable, dimethyl ammonia tetracycline, oxytetracycline and tetracycline), chloramphenicol, macrocyclic lactones, sulfa drugs, furans, nalidixic acid, Pipemidic Acid, chloric lincomycin lactobionate, some Penicillium cable (amoxicillin penicillin, ampicillin) etc. can be oral, and most rapidly absorbed. Surface of aminoglycoside antibiotics such as streptomycin, gentamicin, slime molds) and banquet effect lactam drugs after oral administration absorbs little, can not be used for treatment of systemic infection, but can be used on some pathogenic microorganisms caused by intestinal infection. Applicable to intramuscular or intraperitoneal injection of the drug has 10 amides, aminoglycosides, polymyxin class, chloramphenicol, Lin mycin and sulfa drugs and so on, but some of them also have certain stimulation. Tetracycline, erythromycin and amphotericin B by irritating strong, not suitable for intramuscular or intraperitoneal injection.

Compatibility of drugs

Compatibility of drugs
The incompatibility of drugs is the adverse changes in the use of different drugs in the same prescription. There are 3 kinds of compatibility, that is, the efficacy of the combination of taboo, the physical compatibility of the taboo, the chemical compatibility of the taboo. Physical compatibility is the physical changes that occur between drugs such as adsorption, and the effect of drugs, chemical compatibility, chemical reaction, the combination of different drugs, chemical reaction, and ultimately affect the efficacy or increase the toxicity of drugs.
The phenomenon of drug compatibility is very common, so should pay special attention to, many drugs should be used alone for good. For example: at the same time, Trichlorfon and quicklime can produce poison
More dichlorvos; mixed acidic drugs and basic drugs using possible chemical reactions, the drug failure I of ferrous sulfate can decrease the bactericidal effect of chlorine disinfectant; zeolite and activated carbon has a strong adsorption effect, other drugs should be avoided and their mixed use; the drug tetracycline and not containing iron, calcium, magnesium, aluminum, or feed the same service, because of its complex formation is not easy to absorb the impact absorption, it is not the same service for the latter with sodium bicarbonate, the increase of pH value, can reduce the solubility and affect the absorption of amino sugar; glycosides and cephalosporins combined, can cause acute renal tubule multi point necrosis; cephalosporins and amino sugar glycosides, cephalosporins combination, can increase the renal tubular toxicity.
Dose of antibiotics
Initial antibiotic or antibiotics due to the impure product, not by weight to measure antibiotic intensity, so stipulated that the titer. This particular “unit” is a kind of effective antibiotic composition of the scale. When an antibiotic is made into a pure chemical substance, it can be expressed as a unit of weight. For example, 1 mg penicillin sodium containing 1667 units, or say 1 unit O. 6 micrograms. 1 mg streptomycin alkali containing I OOo unit, namely 1 unit = 1 micrograms; oxytetracycline, erythromycin, kanamycin, neomycin are to its free base 1 mg set for 1 000 units; tetracycline and chlortetracycline element in its hydrochloride salt I mg as 1 000 units I Yi bacteria B to its free base 1 mg set 10 OOo unit (i.e. 1 withdrawal g quite to the 10 units); and business nystatin per 1 mg for 3 been 7oo units.
As mentioned above, the doses of antibiotics is generally to potency unit and a unit of weight not weighing) to represent, for example, oxytetracycline 250 000 units equivalent to 250 mg oxytetracycline soda. Here the 250 mg not weighing, but to a unit of weight. The relationship is
Weight = total number per unit of antibiotic
For example, packaging of oxytetracycline hydrochloride, per capsule containing 250 mg (rather than that of oxytetracycline 250 000 units), such as the purity of the product is 880 units Lu mg, capsulizing actual weighing is computed according to the formula for 294 mg.
Can be seen that the dose of antibiotics have a certain complexity, in the use of the process must be noted.

Antibacterial spectrum of antibacterial drugs

Antibacterial spectrum of antibacterial drugs
Antimicrobial spectrum is the range of varieties of bacteria that are sensitive to the drug. Due to the diversity of its physical and chemical properties, the mechanism of its effect on the bacteria is also different. Some are interfering with bacterial cell wall synthesis, some of the damage of bacterial cell membrane, some of which affect the synthesis of bacterial cell proteins or nucleic acids, which lead to drug sensitive bacteria in the range of different drug. So different drugs have different antibacterial spectrum, some drugs are mainly gram positive bacteria (according to Gram stain reaction, can be divided into gram positive bacteria and gram negative bacteria) sensitive, some drugs are sensitive to gram negative bacteria, but also some of the drug gram positive bacteria and gram negative bacteria are sensitive. The two class is called as antibacterial agents, which is referred to as a broad-spectrum antibiotic. The range of different drugs among different drugs is different. The gram negative bacteria were more sensitive to the drug than gram positive bacteria. Fish pathogenic bacteria is gram negative bacteria, so the use of antibiotics in aquaculture is the majority of broad-spectrum antibacterial drugs.
Drug residues and drug withdrawal period
After drugs into the body, to experience from the absorption, distribution, metabolism, and so on a series of processes, and finally discharged from the body. These processes are in need of a certain period of time, and the length of time is mainly related to the physical and chemical properties of drugs and the variety of animals. The drug is completely eliminated from the fish, some only a few days, while others demand for several months. The residual amount is the content of the drug in the body of the fish market. The content may be very low, but when the human body long-term intake of residual drug, the drug is likely to accumulate in the human body, and then the human body to produce toxic and promote the human body to produce drug resistance. To this end, many countries have used the drug for the approval of the withdrawal period. That is to say, if the use of a certain kind of medicine, the need to stop the medicine for a period of time after the sale, so that the fish in the amount of drug residues to reach the maximum allowable concentration of the following. China has this kind of rules (the people’s Republic of China Ministry of agriculture Announcement No. 235), especially the aquatic products export enterprises in this regard problems must be paid attention to, otherwise it will seriously affect the export of aquatic products, the problems in the export of Japanese eel (Anguilla japonica) had precedent. Even more important is the residue of the drug will seriously affect the health of the vast number of consumers in Ankang.

Prevention and treatment effect and adverse reactions

Prevention and treatment effect and adverse reactions
Drugs for the prevention and treatment of diseases, can produce a beneficial effect on the body, but also produce some adverse reactions to the body. Preventive action can be divided into preventive effect and therapeutic effect. In terms of treatment can be divided into symptomatic treatment and due to treatment, which is temporary and permanent. The former is to reduce or eliminate the symptoms of the disease, the latter is to eliminate the cause of the disease, because the treatment can eliminate the cause of the disease to achieve the effect of a cure, symptomatic treatment can not eliminate the cause, but can relieve symptoms. In clinical practice, should follow the “acute is the treatment of its standard, light is the treatment of its own, the specimen and treatment. Principle.
There are two main types of adverse reactions, that is, side effects and toxic reactions. The former refers to the role of the drug in the treatment of dose not related to the role of the role, generally relatively mild. Such as the drug in the body after the acetylation of acetyl. The lower solubility of sulfacetamide, in urine is acidic easy in renal tubular precipitation and damage the kidneys, this is sulfa drug side effects. Toxicity is usually in the use of large doses, the course is too long or the individual to a higher sensitivity of drug. In order to avoid the occurrence of toxicity, pay attention to do not any more than the drug commonly prescribed amount, in addition to the side effects and toxicity, adverse reaction and allergic reaction, allergy and idiosyncratic reaction, but for fish this several adverse reactions of little significance.
Drug resistance
Although many effective treatment of antimicrobial agents against bacterial diseases in fish, but bacterial disease but throughout the year in place. This is the case, the reason, if the method is correct, but also not the drug has failed, it is the reason for the inhibition of the role of drugs to reduce the pathogenic bacteria. Once effective drugs become inefficient or invalid, it is because pathogens to drugs cause resistance of, called the nature of bacteria resistant Xiaohan, but does not have the properties of common bacteria known as drug sensitive bacteria. Bacterial resistance to antimicrobial susceptibility is reduced. The emergence of drug resistant bacteria is the result of drug selection, which is due to the use of antibacterial drugs. To make the sensitive bacteria inhibited or killed, the original account for a very small number of anti drug strains to the opportunity to multiply into a dominant group, the disease caused by these bacteria is difficult to use conventional drugs to control. However, bacteria are resistant to a particular drug, which may be sensitive to the other, but at times the bacteria are resistant to one drug, and it may become resistant to another, called cross resistance. There are cross resistance in general drug. If, for example, a bacteria resistant to tetracycline, then of oxytetracycline will appear cross resistance, bacteria on a sulfa drug resistance, then to another sulfa drugs certainly with drug resistance. Therefore, in order to make the correct choice of antibiotics, we must carry out the pathogen isolation, and then carry out the drug sensitivity test of pathogenic bacteria, in order to determine the selection of drugs for treatment.
If a drug has been used widely, it will appear to be resistant to the drug. The problem of drug resistance bacteria is not only the problem of drug efficacy, but also can spread the drug resistance to human pathogenic bacteria, which makes the treatment of bacterial diseases difficult to be directly or indirectly. Therefore, the use of antimicrobial drugs in public health has received great attention. In turn, human and animal drug resistant bacteria can also pass through the feces, through various channels to enter the pond, and the drug resistance to the fish bacteria, causing the emergence of drug resistance of pathogenic bacteria, which should also cause people’s attention.
In order to prevent resistance, need to pay attention to the following aspects, that for the first time large dose principle, rotation use different drugs, with medication, long enough for a course of treatment and the use of a new generation of antibacterial drugs such as norfloxacin.

Several important concepts

Several important concepts
1, drug formulation and preparation
Dosage form is a kind of form that can be processed and modulated, easy to use, save and transport. The dosage form can be divided into liquid, gas, solid, semi solid. Preparation is an individual dosage form of a drug.
2 local effect and absorption
The function of the drug is divided into local and absorptive function. The former is the drug to be absorbed into the blood before the play the role of, such as topical disinfectant on the surface of bacteria killing effect and dipterex of Lernaea ‘”absorption refers to the drug is absorbed into the blood after the play the role of, such as chloramphenicol for furuncle hysteria and ulcer disease. The role of the absorption is extensive, which can be involved in all parts of the body. However, due to the different physical and chemical properties, the distribution of them is not the same as in vivo residence time (or in vivo process). For example, after oral absorption, the part of the body is damaged, and the rest are excreted in the urine, and the drug concentration in urine can be used for sensitive storage. Therefore, different drugs have different indications and effects, should be understood in detail.
3 direct and indirect effects
The direct effect is that the function or form of the function of the object is changed. The indirect effect is the secondary function of the body fluid regulation. The bactericidal or antibacterial effect of the antibacterial drugs is the direct action of the drugs in the aquatic drugs play an indirect role in the drug less.
4 synergistic and antagonistic effects
When two or more drugs used in combination, the role can be strengthened due to compensate each other, can be cancelled or reduced, the former synergistic effect, which is called the twist resistance and dispensing can be using the synergistic effects of other drugs, to strengthen the main drug therapy, and should pay attention to avoid the role of anti Chu. But sometimes in order to offset the side by using bamboo Weiyao other drugs Hangzhou antagonistic effect
With the further study of the mechanism of drug action, the antibacterial drugs can be divided into four categories: 1. 2, stationary or slow acting bactericidal agent, streptomycin, card the kanamycin, gentamicin, 3, fast efficient antibacterial agent, chloramphenicol, erythromycin, tetracycline. 4, slow acting agent — sulfa drugs.
This classification has certain directive significance to the application of antibacterial drugs. The combination of the first and the second drugs can produce a synergistic effect, which is due to the destruction of the integrity of the cell wall, and the second type of drug is readily available in the cell. The third drugs can quickly block the synthesis of proteins, so that the bacteria are still in a state of rest, and therefore, when the first type of combination of the latter may lead to the weakening of the latter activity. Third types and second kinds of combination, often can get the cumulative or synergistic effect, generally does not have an antagonistic phenomenon. While the third category of the first class of antibacterial activity without significant influence, and sometimes can produce cumulative effect, similar drugs can also be used in combination.
With the small amount of disinfectant solution containing chlorine or bromine, iodine can greatly enhance the bactericidal ability. There are some substances have synergistic effect on chlorine containing disinfectant.